To meet the demand for wireless data traffic having increased since deployment of 4G (4th-Generation) communication systems, efforts have been made to develop an improved 5G (5th-Generation) or pre-5G Communication system. Therefore, the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post LTE System’.
The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO) array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems.
In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation and the like.
In the 5G system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.
In existing communication networks, comprising user equipment (UE), enhanced node B (eNB), serving gateway (S-GW) and packet data node gateway (PDN-GW), the incoming data via any of several protocols, such as IP, TCP and so on, are converted to blocks of data that can be transported by the Physical layer, by intermediate layers, namely PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control) and MAC (Medium Access Control). These layers provide several functions such as multiplexing, parsing, unpacking, reassembly functions among others.
Any data received by an LTE network is converted to transport blocks by the various layers present in the LTE network in order for the data to be transported by the physical layers. Data transported between various levels come in different sized blocks. Each transport layer communicates the size of each block transported to the next layer and the penultimate layer. The MAC layer generates the MAC Protocol Data Unit (PDU) carrying one or more data blocks for MAC Service Data Units). The MAC layer adds a MAC subheader for each of the MAC SDU in MAC PDU. The size of MAC SDU is indicated in length field of MAC subheader wherein the length field is either 7 bits or 15 bits. Format bit field in the MAC subheader indicates whether length field is 7 bit or 15 bits. The maximum size of MAC SDU that can be indicated using the current MAC subheader is 32767 octets or bytes.
However, the 15-bit field indicating the size of each transport block is insufficient to indicate the size of any data greater than 32767 octets. For emerging communication technologies such as aggregation of large number of carriers or usage of carriers of larger bandwidth to support high data rate, the size of the length field is insufficient to indicate size of the data blocks being transported from any transmitter to a receiver and vice versa. Since the current communication technologies are already deployed with this limitation a backward compatible solution is needed to support larger MAC SDU sizes. Two MAC subheaders can be defined wherein one MAC subheader has a shorter length field and another MAC subheader has longer length field. Network indicates in signaling whether to use first header or second subheader. The disadvantage of this method is that once the network indicates to use header with large length field then irrespective of size of MAC SDU this subheader needs to be used. This leads to unnecessary overhead in each MAC PDU for shorter size MAC SDU.